The invention relates to a system for fastening a rail, which has a sleeper which has a supporting face intended to support the flange of the rail, the supporting face merging, at its sides which extend parallel to the longitudinal extent of the rail to be fastened thereto, into respective levelling faces which are situated at a higher level than the supporting face, an angled mounting plate which has, in each case, a central portion, on the underside of which is formed a support surface by which the angled mounting plate can be placed down on the respective levelling face assigned to it of the sleeper, and a supporting portion which is formed onto the central portion and points downwards from the underside of the latter and which, when the system is fully fitted, bridges the clear space between the flange of the rail and the levelling face, a resilient member which can be placed down on the angled plate and which has, in each case, two holding arms by which, when the system is fully fitted, the resilient member exerts a holding force on the rail, and a clamping member which, when the system is fully fitted, exerts a clamping force on the resilient member.
Rails for rail vehicles usually have a rail flange, with which they stand on the respective surface, a rail stem of small thickness, which rail stem is mounted on the rail flange and a rail head supported by the rail stem, on the upper side of which rail head the rolling surface for the wheels of the rail vehicle is formed. When rolling over such a rail, high strains occur not only due to the weight of the rail vehicle, but the rail is also subjected to high dynamic forces, which occur due to the speed, with which the rail vehicle rolls over the rail. Since the forces acting on the rail during rolling over lead to a considerable deformation of the rail in the moment of rolling over, form and material of the rail are designed such, that the rail can accommodate these deformations also over a large operation period. To this end, however, the rail must also be able to deform and move in the area of its fastenings.
In order to achieve this, a fastening system is required which, on the one hand, holds the rail elastically in the vertical direction such, that its secure fastening on the sleeper is assured and at the same time a sufficient flexibility is present. On the other hand the fastening system applied in each case must be able to absorb the large lateral forces, which are transferred to the rail by the rail vehicle during rolling over.
A fastening system reliably used many times in practice, which fulfils the above mentioned requirements, is known from the setup instruction “Schienenbefestigungssystem W14”, which has been published by the applicant for example with the URL “http://www.vossloh-rail-systems.de”.
The W14 rail fastening system is based on a concrete sleeper, into which an even supporting face for the flange of the respective rail to be fastened is formed. Seen in the longitudinal direction of the rail to be fastened, the supporting face thereby extends over the entire sleeper, while its width, measured transversely to the longitudinal extent of the rail, corresponds approximately to the width of the rail flange. At its two narrow sides the supporting face merges into a respective levelling face which is situated on the same level as the supporting face. Connected to the levelling faces in each case at their narrow side remote from the supporting face is a groove extending over the sleeper and parallel to the longitudinal extent of the rail to be fastened, which groove has an essentially V-shaped cross section.
Additionally, in a central position a reception for a plug or the like is formed into the levelling faces, into which plug a clamping screw can be screwed.
For fastening the rail a so called “angled mounting plate” is placed down onto the levelling faces of the sleeper. These angled mounting plates, which for weight reasons are usually made of a high-strength plastics material, have a central portion, on the underside of which a support surface is formed, with which support surface the angled mounting plate can be placed down onto the respective levelling face assigned to it of the sleeper.
In the angled mounting plate used for the system W14 a supporting portion is formed onto the central portion, which supporting portion, starting from the support surface on the underside of the angled mounting plate, extends downwards and whose form is adapted to the form of the grooves formed into the sleepers. In the mounted position each angled mounting plate sits form-fit in the respective groove assigned to it. With its side lying opposite the supporting portion, however, the angled mounting plates abut laterally against the flange of the rail to be fastened. Lateral forces, which are transferred by the rail onto the angled mounting plate, can thus be absorbed by the angled mounting plate and directed into the sleeper. The support of the angled mounting plates is thereby effected by the side face of the respective groove facing away from the rail.
In order to securely transfer the lateral forces originating from the rail during driving operation onto the respective side face of the groove, the angled mounting plates must have a sufficient strength and form stability. This requirement results in the angled mounting plates used in the known fastening systems, despite them being made of plastics material, having a considerable weight. Also, the plastics used for their production must themselves be resistant in a sufficiently high and long-lasting manner.
For securing the rail against taking off, resilient members are usually used in the known rail fastening systems, which resilient members are made of spring steel. In the rail fastening system W14 as resilient members so called “tension clamps” are used, which are bent from a rod steel. These tension clamps are formed W-shaped and are clamped on the angled mounting plate with their central portion. To this end in the angled mounting plate a through-opening is formed, through which the clamping screw used for clamping the respective tension clamp can be screwed into the respective plug inserted into the sleeper.
After finishing assembly, the tension clamp, in this state being clamped against the sleeper, sits with its holding arms, extending from the central portion, on the flange of the rail to be fastened. The holding arms thus exert elastic forces onto the flange, which forces are on the one hand strong enough in order to prevent excessive taking off of the rail, but on the other hand are so elastic that the rail can sufficiently move up and down in the vertical direction during rolling over of a rail vehicle. In this manner the rail is securely held and can nevertheless compensate its deformations caused by the weight and the driving movement of the rail vehicle.
In order to be able to exert the elastic forces, necessary for holding the rail, durably and securely the tension clamps used in the fastening system W14 and comparably constructed systems each feature a complex form. Thus, the legs of the usually U-shaped central portion at their ends are bent towards each other, so that the clear space remaining between them is smaller than the diameter of the clamping screw used for clamping the tension clamp. In this manner, in the assembled position, the central portion loops around the clamping screw in a securing manner.
From the narrowing area thus formed, the legs of the central portion, in a bending, leading downwards and outwards, respectively lead into a torsion portion, which in the further progression is bent straight. To the two torsion portions of the tension clamp, in a further bending a holding arm is respectively connected, which holding arm, in the non-fastened state, has an arching which, seen in the lateral direction, extends over approximately 160°. In this fashion, when the tension clamp is preassembled on the angled mounting plate, the free ends of the holding arms lie underneath the level of the central portion.
Via a further bending, the free ends of the holding arms each merge into a bending, which bendings, in the plan view, are arranged essentially at a right angle with respect to the central portion of the tension clamp. The free distance between the central portion and the bendings at the end of the holding arms is thereby smaller than the smallest diameter of the tension clamp. In this way it is secured that tension clamps, being collected in a larger container, can not interlock with each other.
Tension clamps of the type described above have proved themselves particularly in the area of such track lines, which are driven in mixed operation, i.e. by high speed trains as well as by heavy load trains. It is contrary to this success, however, that the tension clamps fatigue after a certain operation time and must be replaced. Further, due to their complex form, their production is relatively expensive.
A rail fastening system of the type mentioned above is known from FR 26 34 801 A1. This known fastening system is also based on a concrete sleeper, into which a support surface, extending transversely to the longitudinal extension of the rail to be fastened, is formed. Unlike with the fasting system W14 described above, in this case the support surface is broader than the width of the rail flange. On its narrow sides, extending parallel to the longitudinal extension of the rail to be fastened, the support surface respectively merges in a step into a levelling face, which levelling face, in relation to the level of the support surface, is situated higher than the support surface. In the area of the step a force-carrying face, being positioned essentially at a right angle to the support surface, is formed. In the area between the rail flange and the two steps, also remaining free after assembly, in each case a reception for a plug is formed into the support surface, into which a clamping screw can be screwed.
For fastening the rail, also in the system known from FR 26 34 801 A1 an angled mounting plate is provided. This angled mounting plate, being formed rectangular in the plan view, has a central portion, onto whose one narrow side a supporting portion, extending downwards from the central portion, is formed. In the corner areas of the side facing away from the supporting portion, onto the evenly formed upper side of the angled mounting plate, additionally a guide portion is formed in each case. Both guide portions, with their free ends, extend beyond the central portion. Finally, in a central position a through-opening is formed into the angled mounting plate, through which the clamping screw can be screwed into the plug respectively provided in the sleeper, when the angled mounting plate is positioned on the sleeper.
As a resilient member, in the fastening system known from FR 26 34 801 A1, two flat sheet elements of different length are used, which act in the fashion of a leaf spring.
In the ready mounted state of the system known from FR 26 34 801 A1 an angled mounting plate respectively sits in one of the spaces remaining free in the area of the support surface at the side of the rail. The angled mounting plates thus bridge over the distance between rail flange and step, so that their supporting portion, with its contact surface, abuts the force-carrying face, assigned to it, of the sleeper, while the central portion, with its side face facing away from the supporting portion, laterally abuts the rail flange. In this case the guide portions of the angled mounting plates lie on the rail flange, so that the angled mounting plate stands on the support surface in the area of its supporting portion only.
In this assembly state, the upper side of the angled mounting plates is positioned slightly lower than the level of the respective levelling face of the sleeper. On the upper side of the angled mounting plates, in each case the longer of the resilient members is arranged such, that with its one end it is supported on the rail flange and with its other end it is supported on the levelling face. The shorter member is positioned on the longer resilient member. Both resilient members are respectively clamped by a clamping screw acting as a clamping element, which clamping screw is screwed into the sleeper through the resilient members and the respective angled mounting plate. The plate-like resilient members thus, in the fashion of a leaf spring, exert the required elastic holding forces onto the rail flange.
Rail fastenings of the type known from FR 26 34 801 A1 are used in the area of tracks, which are exclusively driven in high speed operation. For the stresses and deformations of the rail thereby occurring, the elasticity of the known system suffices. However, for tracks driven in mixed operation this known system proves not to have sufficient fatigue strength. In particular, the overall elasticity of the system is not high enough, in order to secure a sufficient movability of the rail at the same time as sufficiently high holding forces in heavy load operation.
Apart from the above explained prior art, from practice a fastening system is known, in which a resilient member of the type mentioned initially, offered under the designation “Spannklemme SKL2”, is used. This tension clamp has a U-shaped central portion, whose legs extend parallel, and at their ends respectively merge into a respective holding arm in a continuous bending leading outwards without deviations. Starting from the end of the straight leg carrying it, each holding arm is bent by approximately 185°, so that its free end is respectively arranged obliquely with respect to the leg concerned, and the imaginary extensions of the holding arms, in the plan view, intersect in a point, which lies far outside the central portion.
The radius of the bending of the holding arms thereby corresponds precisely to the radius, by which the U-shaped central portion is bent between its legs. The diameter of the partial circle, in each case encompassed by the holding arms, is thus the same as the clear width between the legs of the central portion. Since at the same time the length of the legs of the central portion approximately corresponds to twice the clear width between them, the free ends of the holding arms, in the plan view, are approximately positioned at the level of the position, at which the holding arms are connected to the respective leg carrying them. Thereby the holding arms, seen in their mounted position, are inclined downwards approximately after half of the bending fulfilled by them.
For fastening a rail with the aid of one of the above described SKL2 tension clamps, a so called “fin plate” is mounted on a sleeper. This fin plate carries a fin being aligned parallel to the longitudinal extent of the rail. After positioning the rail to be fastened, the known tension clamp, with its middle section, is placed on the fin such, that the clamp's bent partial section, connecting the legs of the central portion, lies on the fin facing away from the rail, while the free ends of the holding arms stand on the rail flange. With the aid of a pressure plate and a clamping screw the tension clamp is then clamped against the fin plate, so that, via its holding arms, it exerts the necessary elastic holding force onto the rail flange.
In practical operation the long legs of the known tension clamp are subject to work done on bending and torsion. This mixed stress leads to a limited fatigue strength of the known tension clamp. Furthermore, the relatively short holding arms, also in combination with the long legs of the central portion, in particular during the high required holding forces during heavy load or high speed operation, do not provide sufficient elastic flexibility, in order to permanently secure the necessary movability of the rail in the vertical direction at the same time as a reliable holding.
Starting from the prior art described above it was the object of the invention to provide a system for fastening rails, which can be manufactured cost-efficiently, and which, besides being able to be permanently loaded in an improved manner and exhibiting a prolonged lifetime of its components, is able to exert high holding forces at optimised elastic properties.
Starting from the prior art explained above this object has been met by a system of the initially mentioned type, which according to the invention is characterised in that, when the system is fully fitted, the axis along which the clamping force exerted by the clamping member acts passes through the levelling face.
In a system according to the invention, unlike in the prior art, the lateral forces exerted by the rail during operation are transferred by the angled mounting plate into the sleeper at a position, which lies in front of the area, in which the clamping member, used for clamping the resilient member, is mounted on the respective sleeper. This leads to the clamping means themselves remaining essentially free from lateral forces. The same applies to the parts of the angled mounting plate, which lie beyond the border of the transition of the support surface to the levelling face. These can therefore be accomplished in a particularly simple manner. Since the angled mounting plate does not have to exert lateral forces in the area lying on the levelling face, it can, without constrains, be designed such, that it has optimum guiding properties for the resilient member being respectively supported on it. Since due to the force introduction according to the invention also the lateral relative movements between the resilient member and the angled mounting plate, the clamping element and the angled mounting plate as well as the angled mounting plate and the sleeper can be reduced to a minimum, the abrasive wear of the angled mounting plate and the sleeper is also reduced to a minimum.
As a result, thus a system for fastening a rail is provided, which is optimised with regard to its functioning, its weight and the lifetime of its components, which can be produced at reduced costs and at the same time possesses optimised using properties.
The acting principle underlying the system according to the invention can be realised in practice for example by using a sleeper, which has a supporting face intended to support the flange of the rail, the supporting face merging, at its sides which extend parallel to the longitudinal extent of the rail to be fastened thereto, into respective levelling faces which are situated at a higher level than the supporting face, wherein there is associated with each levelling face a formed element for fastening a clamping member in place, which clamping member, when the rail is fitted, holds clamped, with a clamping force, a resilient member which exerts a holding force on the rail, and in that, in relation to the transition between the supporting face and the levelling face associated therewith, each of the formed elements is arranged to be spaced away from the supporting face in the direction of the levelling face concerned in such a way that, when there is a clamping member fastened to the sleeper, the axis along which the clamping force produced by the clamping member acts passes through the levelling face associated with the given formed element.
In a sleeper thus designed, the introduction of the force needed for clamping the respectively used resilient member occurs at a position of the sleeper, which lies beyond the border of the transition of the supporting face to the levelling face. Accordingly, the position provided at the sleeper for fastening the clamping member lies at least on the border of the transition between the supporting face and the levelling face, and in this case such, that the axis, via which the force exerted or absorbed by the clamping member acts, does not extend through the supporting face but first through the levelling face. Such a sleeper is provided such that the force clamping the resilient member, seen from the supporting face, is introduced into the sleeper behind that surface, which limits the supporting face in the area of the transition to the levelling face. Thus, it is possible to support an angled mounting plate, provided for lateral support of the rail, in the area of the transition, without the means provided for clamping the resilient member being stressed.
A particularly good introduction of the lateral forces coming from the rail during operation into the sleeper can in this connection be achieved by the transition between the supporting face and the levelling face being of a stepped form. For this purpose the force-carrying face laterally limiting the supporting face in the area of the transition to the levelling face is arranged such, that the angle made between the lateral face and the supporting face is 75° to 105°, particularly 85° to 95°.
The form of the levelling face of the sleeper used preferably is generally dependent on the outlay of the angled mounting plate used for fastening the rail, the corresponding resilient member and the clamping means, which is used for clamping the resilient member. A particularly simple outlay results in this context when the supporting face and the levelling face are positioned in planes arranged parallel to one another.
The collection of water on the sleeper can be counteracted if at least one of the surfaces which adjoin the levelling face and are remote from the supporting face is formed to slope down from the levelling face. Thereby it is favourable if the surface which adjoins the levelling face merges steplessly into the levelling face, so that rain water hitting the levelling face can drain off unobstructedly.
The sleeper used in a system according to the invention is preferably produced from a concrete material, which is economically available and possesses the toughness required for receiving the forces. Alternatively the sleeper can also be produced from a suitable plastics material or a mixed material from plastics material and concrete material. The concrete material can further contain reinforcement components such as carbon fibre, glass fibre or the likes.
As a forming element for fastening the clamping member an opening can be formed into the sleeper of the above scribed type, used in the system according to the invention, into which for example a plug for a screw serving as clamping member can be inserted. Alternatively for fastening the clamping member clips, bows, pins, hunches or comparable elements can be formed onto the sleeper or be provided in other ways, which elements receive the forces required for clamping the resilient member.
An angled mounting plate preferably used in the fastening system according to the invention is characterised in that the angled mounting plate has a central portion, on the underside of which is formed a support surface by which the angled mounting plate can be placed down on a levelling face of the sleeper, and a supporting portion which is formed onto the central portion and points downwards from the underside of the latter, which supporting portion has a first contact face which comes to bear against the rail in the fitted position, and a second contact face situated opposite which rests against the sleeper in the fitted position, and a through-opening formed in the central portion for a clamping member, the centre axis of which through-opening, passing through the central portion, extends outside the supporting portion and adjacent to the latter's second contact face.
The form of such an angled mounting plate allows for the mounting plate to be mounted such, that the lateral forces originating from the rail to be fastened in operation are transferred to the sleeper via the supporting portion only, which sleeper carries the rail and the components used for its fastening. In order to achieve this, the supporting portion according to the invention is formed onto the central portion of the angled mounting plate at a position, which in the fitted state of the mounting plate with respect to the rail to be fastened lies in front of the central axis of the through-opening of the mounting plate, which axis is guided through the central portion. The central portion of the angled mounting plate, however, remains essentially free from the lateral forces. Thus, it is exclusively available for guiding a resilient member, which can be mounted on the angled mounting plate and which exerts the necessary holding forces in the vertical direction for holding the rail. In order to securely hold and guide the resilient member, only small material amounts are required in the area of the central portion, so that such an angled mounting plate has a considerably smaller weight compared with the known angled mounting plates fulfilling a corresponding functional range.
Together with the material saving achieved in the manner described above angled mounting plates designed in such a way have an increased lifetime. This is also achieved in that only the supporting portion is subjected to the forces directly emanating from the rail, while the central portion is essentially only loaded with the clamping force acting on the resilient member. Mixed loads, as they were unavoidable in the prior art, thus, if at all, only occur to small extents, so that in particular the abrasive wear due to relative movements between the angled mounting plate and the sleeper is reduced to a minimum.
Particularly good conditions in the transfer of the forces originating from the rail can be achieved, if the angle made between the support surface and the second contact face of the supporting portion is 75° to 120° and in particular 100° to 115°.
An improved protection against twisting, slipping or spreading of the resilient member to be mounted on the angled mounting plate can further be achieved, if additionally to the other features of the angled mounting plate, on its upper side opposite from the underside, the central portion has formed elements for guiding of a resilient member for applying a holding force to the rail, which resilient member can be placed down on the angled mounting plate.
These formed elements can for example be constructed in the form of legs connected to the central portion, which legs follow the form of the resilient member to be fastened on the angled mounting plate.
For improving the isolation of the angled mounting plates a collar, which extends round the edge of the through-opening at least in portions, can be formed on the underside of the angled mounting plate. In the fitted angled mounting plate, this collar then sits in a corresponding reception of the sleeper, into which also the clamping means used for clamping the respective resilient member engages.
For improving the guiding of the resilient member in the clamped state as well as for protection against the penetration of moisture, which collects on the angled mounting plate, into the area of the through-opening it can be favourable, to provide in the region of that edge of the through-opening which is associated with the upper side of the central portion, a collar projecting from the upper side. This collar also preferably extends round the edge of the through-opening.
Further weight savings can be accomplished in that the width of the central portion is dimensioned smaller than the width of the support portion.
Angled mounting plates used in a system according to the invention are preferably produced from a plastics material. However, other materials, such as metals and comparable materials, can also be used if the forces occurring in operation require it.
A resilient member particularly suitable for use in a fastening system according to the invention is characterised in that the resilient member has a U-shaped central portion whose legs merge into a respective one of holding arms, which holding arms, starting from the legs of the central portion which are respectively associated with them and moving away in a lateral direction, are bent into a curve which extends continuously and without deviations through more than 180°, and whose radius is more than half the clear width between the legs of the central portion. Such a resilient member is characterised firstly in that its holding arms extend from the U-shaped central portion of the resilient member in a continuous bending, having constantly the same curvature. Thereby the radius, with which the holding arms are bent, is so large, that the clear width of the space respectively limited by the holding arms is greater than the distance between the legs themselves. Through this forming in the area of the bent holding arms a great length is available, over which the holding arms are elastically flexible. The form of the holding arms bent in a large radius leads to the holding arms, in the loaded state, essentially only being subjected to torsional strain. Since at the same time the length of each leg of the central portion is short compared with the length of the holding arm respectively connected to it, these legs also are only negligibly loaded with bending stress in the fully fitted state. A mixed load affecting the bending endurance is thus avoided, so that such a resilient member can be used over an operational time considerably longer than known resilient members.
Thereby, the resilient member preferably used in a system according to the invention has an improved operational reliability compared with the prior art. Due to the wide extent of the holding arms the central portion of such a resilient member can be mounted without problems such, that it forms a protection against tilting of the resilient member under the forces occurring in practical operation.
A further advantage of the above described resilient member lies in the amount of material needed for its production is reduced to a minimum. Therefore, also the weight of such a resilient member is considerably reduced in comparison with the weight of known resilient members of similar capacity.
The elasticity, with which the resilient member is capable of exerting the holding force produced by it, can be optimised in that seen in the plan view, the extent, as measured parallel to a given leg of the resilient member, of the region which is defined by the holding arms is in each case greater than the length of that leg of the central portion which is associated with the given holding arm. This embodiment further enables a simple fitting of the resilient member, since the holding arms can be placed onto the flange of the rail to be fastened in an easy manner, and at the same time sufficient space is available for fastening the central portion. It serves the same purposes if the bending of the holding arms is made such, that its free ends are directed towards the central portion.